Hop drier



Dec. 14, 1954 R. L. NAUMAN ETAL HOP DRIER Filed June, so, 1952 5 Sheets-Sheet 1 INVENTORS Dec. 14, 1954 R. L. NAUMAN ETAL HOP DRIER 5 Sheets-Sheet 2 Filed June 30, 1952 Whv m INVfyTORJ' fag/Md L. arrzan 11/ Idm Z' Beala y Haw-y 4-50-9215;

Dec. 14, 1954 R. L. NAUMAN arm HOP DRIER 5 Sheets-Sheet 3 Filed June 30, 1952 INV NTORS (gym/2i L- United States Patent 2,696,680 Patented Dec. 14, 1954 Fice HOP DRIER Raymond L. Nauman, William T. Beale, and Harry A. Sorensen, Pullman, Wash, assignors to State College of Washimton, Pullman, Wash.

Application June 30, 1952, Serial No. 296,418

Claims. (Cl. 34203) The present invention relates to improvements in driers for green crops.

Our invention is particularly applicable to the drying of such materials as hops. It is the principal purpose of our invention to provide a novel drier wherein the green material to be dried is caused initially to traverse the upper part of the drying enclosure, then is reversed and is caused to traverse the same enclosure in a lower flight so that the dried material is delivered at the loading end, and wherein the drying medium is so directed that the portion thereof passing through the partially dried material of the lower flight must also pass through the incoming wetter material that is traversing the upper portion of the enclosure.

It is also a purpose of the invention to provide in a drier of the character above described, means to supplement the drying medium for the upper flight of the material including a recirculating apparatus taking part of the drying medium that has gone through both flights and re-heating it and again distributing it in the enclosure getwleen the upper and lower flights of the material being More specifically it is the purpose of the present invention to provide an improved drier for such crops as hops and the like wherein the material to be dried is initially fed into the drying enclosure between two confining conveyors, one of which completely encircles the other. The construction is such that the conveyors carry the wet material through the length of an enclosure and then lower the material and return it through the same enclosure inverted so as to obtain more uniform drying. The conveyor delivers the material at the same end of the enclosure where it is received but at a lower level. On the lower flight the material has a heated gaseous drying medium flowing upwardly through it. The gaseous medium passing through the material on the lower flight is supplemented by additional heated dry gas. This pro-' cedure provides the necessary gas to remove the desired amount of moisture from the wetter material and avoids subjecting the substantially dried material to excessive temperatures and speeds of the drying medium.

Our invention will be described in connection with the drying of hops which are used for brewing purposes. It is well known that the quality of the hops for this purpose depends a great deal upon the way in which they are dried. Tests have shown that while temperatures up to 230 degrees F. may be used in initially drying the wet hops without damaging their lupulin, it is necessary to reduce the drying temperature as the hops become drier. According to our invention our improved drier is so constructed as to provide means for subjecting the wet hops, as they enter the drier and are initially dried, to a rela-- tively high temperature drying medium in substantially greater volume than can be used through the hops as they approach the required ultimate dryness. In this initial drying a reverse current flow is to a certain degree provided. However, in the final drying, the amount of drying medium is reduced because of the nature of the construction and the direction of flow of the drying medium in the drying enclosure beneath the flight of the hops receiving the final drying, is in such a direction that the temperature at the final point of drying is at the lowest 7 It should be understood however, that the drawings and description are illustrative only and are not intended to lirrrit 'the invention except insofar as it is limited by the claims.

In the drawings:

Figure 1 is a somewhat diagrammatic plan view of a hop drier embodying our invention;

Figure 2 is an enlarged sectional view taken on the line 22 of Figure 1;

Figure 3 is an enlarged sectional view taken on the line 33 of Figure 1;

Figure 4 is a sectional view taken on the line 44 of Figure 3; and

Figure 5 is a sectional view taken substantially on the line55 of Figure 2.

Referring now in detail to the drawings, the present invention is embodied in a drier which comprises an elon gated enclosure 10. The main parts of the enclosure 10 are supporting channels 11 and 12, floor panels 13, side panels 14 and 15, cover panels 16 and 17, and end panels 18, 19, 2t) and 21. The several panels are made of sheet metal and are reenforced by angle irons, 13a, 14a, 15a, 16a, 17a, 18a, 19a, 20a and 21a. These angle irons also serve as means to connect the several panels to each other to complete the enclosure 10. The end panel 18 terminates above the bottom of the enclosure to provide an open space to receive an outlet conduit 22 from a drying medium supply unit 23. This supply unit is conventional and comprises a fan with its drive motor and a burner with its supply nozzle where a suitable fuel such as fuel oil is burned to heat the air brought in by the fan so that a'suitaole supply of drying medium at the proper temperature may be supplied to the enclosure through the conduit 22.

The enclosure has an outlet conduit 24 at the top thereof. This conduit 24 opens into the enclosure 10 through one of the side panels 15. The conduit 24 extends laterally and downwardly and leads into another heating unit 27 for supplying a drying medium to the enclosure. This heating unit comprises a fan, a motor, a burner and its supply nozzle. A fan 25 is provided for drawing air from the enclosure 10 through the conduit 24. A motor 26 drives the fan 25. An outlet 28 for the heated drying medium leads from the unit 27 into the side of the enclosure. The recirculated air drawn from the en closure 10 through the conduit 24 is reheated over the unit 27 and mixed with additional heated air and gases of combustion and returned to the enclosure 10 through the conduit 28.

At the other end of the enclosure 10, a feed conveyor 33 and a delivery conveyor 34, are provided. The feed conveyor 33 is supported on two frames 29 and 30 constructed of angle iron and suitably secured to the side panels 14 and 15 and to the channels 11 and 12. The feed conveyor 33 extends transversely of the enclosure and has its entrance end in a hopper 35 which is provided at one side of the enclosure. The details of the feed conveyor 33 will be described more fully hereinafter. The delivery conveyor 34 is located beyond the end of the enclosure for carrying away the dried material to any suitable loading or storing facility.

In order to carry the hops, etc. to be dried through the drying enclosure, two foraminous conveyors 36 and 37 are provided. The conveyors, as illustrated, are essentially the same in construction. They are belts composed of wire mesh, the side edges of which are attached to sprocket chains 38 and 39. To prevent excessive sagging transversely between the belts, the wire mesh is secured to transversely running angle irons 40. The end of these angle irons also may be secured to the sprocket chains.

The sprocket chains 38 extend over two pairs of sprocket wheels 41 and 42 that are located over the feed conveyor 33. They then extend beneath a pair of sprocket wheels 43 and are guided by upper guide rails 44 and lower guide rails 45 on the side panels 14 and 15 lengthwise of the enclosure to the right hand end of the enclosure where two pairs of sprocket wheels 46 and 47 guide the conveyor 36 down to the level of the conduit 22. Guide rails 48 support the conveyor 36 in its lower flight to the right hand end of the enclosure where the conveyor 36 is carried by pairs of sprocket wheels 49, 50 and 51 downwardly beneath the delivery conveyor'34.

The conveyor 37 is supported beneath the feed conveyor 33 by sprocket wheels 52 and guide rails 53 and 54. The frame 29 carries one sprocket wheel 52 and one guide rail 53. The frame carries the other sprocket wheel 52 and the other guide rail 53. The guide rails 54 are mounted on the side panels 14 and 15. The guide rails 54 support the conveyor 37 to the right hand end of the enclosure where the conveyor is guided downward over pairs of sprocket wheels 55 and 56. The conveyor 37 returns to the loading and delivery end of the enclosure, being guided at both sides by guide rails 57 beneath it and guide rails 58 above it which restrict its movement up or down. Two sprocket wheels 59 on the frames 29 and 30 complete the means for guiding the conveyor 37. It will be obvious of course, that any of the sprocket wheels may serve as the driving means for maintaining the conveyors 36 and 37 in motion.

It will be noted from an examination of Figures 2 and 3 that the space between the upper flights of the conveyors 36 and 37 gradually decreases from the right hand end to the left hand end of the enclosure 18' so that the depth at the right hand end of the enclosure of the space between the conveyors is only about threefourths the depth at the left hand end. This tapering feed channel is provided to take care of the shrinkage of the hops as they traverse the upper flight of their travel through the enclosure. This permits the conveyor to hold the wet hops as they are being advanced and prevents as much as possible, the movement of the hops while they are being dried. By the time the hops have reached the right hand end of the enclosure, most of the shrinkage will have taken place. However, the space between lower flights of the conveyors 36 and 37 is also made slightly deeper at the left hand end than it is at the right hand end to allow for any further shrinkage of the material. A deflector plate 60 may be provided between the feeder conveyor 33 and the top of the conveyor 37 so as to direct the hops into the conveyor 37.

The conduit 28 enters the enclosure 10 between the upper and lower flights of the inner conveyor 37. Within this space there is an elongated inverted pan shaped shell 61 which is spaced from the upper and lower flights of the conveyor 37 and which is spaced from the side panels 17 of the enclosure. A baffle plate 62 is spaced from the lower edge of the inverted pan 61 and is of the same dimensions as the pan 61 so that a narrow air passage 63 is provided between the pan 61 and the baifle plate 62. Cross bars 64 support the pan 61 and cross bars 65 support the baflie 62. The heated drying medium entering the enclosure through the conduit 28 flows into the pan 61 and spreads out throughout the enzlgpsure 10, escaping from the pan through the passage The operation of the drier is as follows: The green material to be dried is fed into the hopper and is distributed onto the conveyor 37 by the feed conveyor 33. This feed conveyor comprises a series of links 33a which are rigid and hinged together at their meeting points. The links travel over rectangular guiding members 66 and 67 which are secured on shafts 68 and 69. The shafts are driven by a suitable source of power, not shown. The rate of feed of the hops is preferably such as to substantially fill the space between the upper flights of the conveyors 37 and 36 at the left hand or entrance end of the enclosure. The hops are carried between the conveyors 36 and 37 to the right hand end of the machine where they pass down onto the lower flight of the conveyor 36 so that on the return travel through the enclosure, the conveyor 36 is the supporting conveyor and the conveyor 37 overlies the material being conveyed. The material is thus inverted midway of the drying cycle so that the direction of flow of the drying air through thelhops is reversed during the last half of the drying cyc e.

The primary supply of drying medium, consisting of air and the gases of combustion of the fuel employed, enters through the conduit 22 and first contacts the material being dried on the lower flight. The air travels lengthwise of the enclosure beneath the lower flight of the conveyor 36 in the same direction that the material itself is moving. It is easy to avoid over heating or burning of the finally dried material since the coolest place in the enclosure is at the lower left hand end of the enclosure as shown in Figure 2. The final drying can be' carried out with very dry air at a safe temperature. The primary air, after flowing through the hops on the lower flight of the conveyor 36, is then mingled with the air coming through the passage 63 from the conduit 28 and the entire volume of air from the sources 22 and 28 passes upwardly through the wetter hops carried on the upper flight of the conveyor 37. A part of the air, that part which strikes the wettest of the hops, is allowed to escape to atmosphere by leaving the enclosure 10 open at the top for part of its length. That part of the air under the top panels 16 is drawn off through the outlet conduit 24 and is recirculated with added air after being heated by the unit 27.

The drier described hereinbefore is particularly useful in the drying of hops. In. traversing the enclosure 10 in the manner described from the feed conveyor 33 to the delivery conveyor 34, the green hops are progressively dried with a minimum amount of heated drying medium. In the upper part of the enclosure, at the beginning of the drying operation, the necessary, large volume of dry air is available from the primary air that passes up through the hops carried on the lower flight of the conveyor 36, and from the additional supply through the inlet conduit 23. The primary air is not saturated in passing through the lower bed of hops. It can take up more moisture from the upper wetter bed of hops on the upper flight of the conveyor 37.

Higher temperature air can be used in the upper part of the enclosure to speed up the initial drying. The primary air that has passed through the lower bed of hops is brought into contact with the baflie plate 62 and mixed with the hotter secondary air that flows through the passage 63. This results in increased capacity of the primary air to take up moisture from the upper bed of hops, and a blending of the secondary air with the primary air before they reach the upper bed of hops. The lower bed of hops, being partially dried, does not offer so much resistance to the air flow. The pressure drop across the lower bed can be kept low, as this pressure is the difference between the pressure existing between the beds and the pressure existing below the lower bed. The hops are shaken up and turned over when they drop from the upper conveyor flight to the lower conveyor flight, so that better air contact is obtained in the final drying.

It is believed that the nature and advantages of our invention will be clear from the foregoing description. Having thus described our invention, we claim:

1. A drier of the character described comprising an elongated enclosure having closed side walls, a bottom wall and end walls, an outer flexible foraminous endless conveyor entering one end of the enclosure and extending from side wall to side wall above the bottom of the enclosure to proximity to the other end of the enclosure, an inner flexible foraminous endless conveyor supported in the enclosure within and spaced from the first named conveyor, means to fill the space between the upper flights of said conveyors, where they enter the enclosure, with the material to be dried, means to remove dried material from the lower flights of the conveyors where they emerge from the enclosure, means to supply a heated gaseous medium to the enclosure beneath the lower flight of the outer conveyor, and means to supply additional heated gaseous medium to the enclosure between the upper and lower flights of the inner conveyor, said last named means comprising an inverted pan within and spaced from the side walls of said enclosure and a baffle plate beneath the pan adjacent to the peripheral wall of the pan.

2. A drier of the character described comprising an elongated enclosure having closed side walls, a bottom wall and end walls, an outer flexible foraminous endless conveyor entering one end of the enclosure and extending from side wall to side wall above the bottom of the enclosure to proximity to the other end of the enclosure, an inner flexible foraminous endless conveyor supported in the enclosure within and spaced from the first named conveyor, means to fill the space between the upper flights of said conveyors, where they enter the enclosure, with the material to be dried, means to remove dried material from the lower flights of the conveyors where they emerge from the enclosure, means to supply a heated gaseous medium to the enclosure beneath the lower flight of the outer conveyor, and means to supply additional hotter gaseous medium to the enclosure between the upper and lower flights of the inner conveyor, said last named means comprisi g an inverted pan within and spaced from the side walls of said enclosure and a bafiie plate beneath the pan adjacent to the peripheral wall of the pan.

3. A drier of the character described comprising an elongated enclosure having closed side walls, a bottom wall and end walls, an outer flexible foraminous endless conveyor entering one end of the enclosure and extending from side wall to side wall above the bottom of the enclosure to proximity to the other end of the enclosure, an inner flexible foraminous endless conveyor supported in the enclosure within and spaced from the first named conveyor, means to fill the space between the upper flights of said conveyors, where they enter the enclosure, with the material to be dried, means to remove dried material from the lower flights of the conveyors where they emerge from the enclosure, means to supply a heated gaseous medium to the enclosure beneath the lower flight of the outer conveyor the encolsure having the top open from side to side from the middle thereof to the end where the wet material enters the enclosure, means, including a cover over the remainder of the enclosure, a duct extending from the covered portion of the enclosure above the upper flight of the conveyors, away from the enclosure, a fan in said duct and a gas heating means connected to the duct, for collecting and reheating part of the drying medium from the enclosure above the upper flight of the outer conveyor, and means to return the reheated drying medium to the space within the enclosure between the upper and lower flights of the inner conveyor.

4. A drier of the character described comprising an elongated enclosure having closed side walls, a bottom wall and end walls, an outer flexible foraminous endless conveyor entering one end of the enclosure and extending from side wall to side wall above the bottom of the enclosure to proximity to the other end of the enclosure, an inner flexible foraminons endless conveyor supported in the enclosure within and spaced from the first named conveyor, means to fill the space between the upper flights of said conveyors, where they enter the enclosure, with the material to be dried, means to remove dried material from the lower flights of the conveyors where they emerge from the enclosure, the upper flights of said conveyors converging from the end where they receive the material to be dried to the other end of the enclosure, means to supply a heated gaseous medium to the enclosure beneath the lower flight of the outer conveyor, and means to supply additional heated gaseous medium at a higher temperature to the enclosure between the upper and lower flights of the inner conveyor.

5. A drier for green crops such as hops comprising an elongated enclosure having closed side walls, a bottom wall and end walls, an outer flexible foraminous endless conveyor, an inner flexible foraminous conveyor within and spaced from the first named conveyor, said conveyors entering the enclosure at one end thereof and extending from side wall to side wall above the bottom of the enclosure to proximity to the other end of the enclosure, whereby to provide between the conveyors a U-shaped channel for the green crop to enter one end of the enclosure near the top and pass through the length of the enclosure and return, and exit from the same end of the enclosure near the bottom, means outside the enclosure to fill the space between the upper flights of said conveyor with the green crop as they enter the enclosure, the upper flights of said conveyors converging from the loading end to the other end of the enclosure, means to cause a flow of heated drying gas under pressure lengthwise of the enclosure toward the exit end of the lower flight and beneath the lower flight of the outer conveyor, whereby said gas is caused to pass up through the crop confined in said channel, means above the top flights of said couveyor adjacent to the end of said enclosure most remote from the end where the conveyors enter for drawing oil gas that has risen through the crop, means for reheating the gas drawn off to a temperature higher than the temperature at which the gas originally entered the enclosure, means returning the reheated gas to the space between the upper and lower flights of said conveyors, and means between said flights to mix the reheated gas with the gas rising through the lower flight of the conveyors.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,915,648 De Reamer June 27, 1933 2,152,939 Wentworth Apr. 4, 1939 FOREIGN PATENTS Number Country Date 54,181 Germany Oct. 31, 1890 94,311 Austria Sept. 25, 1923 

